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81.发明授权Magnetic reproducing apparatus having circuit for preventing reversal of white peak 失效具有防止白色反转的电路的磁性再现装置
公开(公告)号：US5220427A
公开(公告)日：1993-06-15
申请号：US422884
申请日：1989-10-19
申请人： Seiichi Mikami
发明人： Seiichi Mikami
CPC分类号： H04N5/9315 , H04N5/93
摘要： A magnetic reproducing apparatus wherein reversal of white peak is reduced in the luminance signal reproducing system. This magnetic reproducing apparatus includes a negative feedback circuit for applying a negative feedback to an input FM signal obtained by reproducing a magnetic recording, and a demodulation circuit responsive to an FM signal outputted from the negative feedback circuit to demodulate it, thus to provide a reproduced luminance signal. The negative feedback circuit includes an amplifier circuit having a non-inverting input terminal to which FM signal or a signal corresponding thereto is delivered, a first limiter circuit for applying amplitude limiting to the output signal from the amplifier circuit, and a delay circuit for delivering, to the amplifier circuit, a delay signal which lags the amplitude limited signal from the first limiter circuit by a phase angle of 90 degrees in the carrier frequency band of the FM signal.
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82.发明授权
公开(公告)号：US5212834A
公开(公告)日：1993-05-18
申请号：US349161
申请日：1989-05-09
申请人： Jouni Nuqvist
发明人： Jouni Nuqvist
摘要： An FM intermediate-frequency circuit into which there is integrated at least a limiter-amplifier (1A) and a phase-locked loop which contains a VCO (4). The limiter-amplifier also includes a level detector. The dynamic range of the level detector is expanded without having to use excessive limiter-amplifier amplification, which would cause oscillation problems, by placing in parallel with the limiter-amplifier (1A) at least a second limiter-amplifier (1B), in connection with which there is also a level detector. The level of the input signal of the second limiter-amplifier (1B) is dropped as compared with that of the first limiter-amplifier (1A) by means of a dividing circuit (R1, R2). The signals (1A, 1B) obtained from the level detectors are combined to form one level detection signal (ITOT). If the signals are in the form of current, the combining can be carried out directly by summing the signals.
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公开(公告)号：US4731872A
公开(公告)日：1988-03-15
申请号：US827327
申请日：1986-02-07
申请人： Clyde Washburn, Jr.
发明人： Clyde Washburn, Jr.
摘要： An improved FM receiver is disclosed incorporating improved oscillating limiter circuitry having an electrically tunable bandpass filter which is phase modulated by the baseband signal the phase of which has been advanced in accordance with the formula: ##EQU1## wherein td.sub.1 equals the time delay through the limiter, td.sub.2 equals the time delay through the feedback filter, td.sub.3 equals the time delay through the demodulator and f.sub.n equals the frequency of the respective baseband components.
摘要翻译： 公开了一种改进的FM接收机，其结合改进的振荡限制器电路，其具有电可调谐带通滤波器，该电可调谐带通滤波器由基带信号相位调制，该基带信号的相位根据以下公式推进：其中td1等于通过限幅器的时间延迟 ，td2等于通过反馈滤波器的时间延迟，td3等于通过解调器的时间延迟，fn等于各个基带分量的频率。
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公开(公告)号：US4679247A
公开(公告)日：1987-07-07
申请号：US717250
申请日：1985-03-27
申请人： Clyde Washburn, Jr.
发明人： Clyde Washburn, Jr.
摘要： An improved FM receiver is disclosed incorporating improved oscillating limiter circuitry having an electrically tunable bandpass filter and variable attenuator in regenerative feedback relationship around the limiter. The electrically tunable bandpass filter is responsive to DC components and high frequency noise components of the demodulated video baseband signal. The variable attenuator is responsive to the carrier-to-noise ratio of the received FM signal whereby the amount of regenerative feedback around the limiter will vary inversely proportional to charges in the carrier-to-noise ratio.
摘要翻译： 公开了一种改进的FM接收机，其结合改进的振荡限制器电路，其具有电可调谐带通滤波器和在限制器周围的再生反馈关系中的可变衰减器。 电可调带通滤波器响应于解调的视频基带信号的DC分量和高频噪声分量。 可变衰减器响应于所接收的FM信号的载波噪声比，由此限制器周围的再生反馈量将与载波噪声比中的电荷成反比。
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公开(公告)号：US4588956A
公开(公告)日：1986-05-13
申请号：US673936
申请日：1984-11-21
CPC分类号： H03G11/06 , H03G11/002 , H03G7/001
摘要： An amplifier-limiter device intended to amplify a received signal up to a predetermined value. The device comprises 2n integrated circuits of the emitter coupled logic type which are connected in series, these integrated circuits forming n successive pairs and each pair having associated with it a compensating circuit which compensates for the linear distortion caused by the integrated circuits of the pair.
摘要翻译： 一种用于将接收到的信号放大到预定值的放大器限幅器装置。 该装置包括串联连接的发射极耦合逻辑类型的2n个集成电路，这些集成电路形成n个连续对，并且每对具有相关联的补偿电路补偿由该对的集成电路引起的线性失真。
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公开(公告)号：US4232268A
公开(公告)日：1980-11-04
申请号：US3028
申请日：1979-01-12
申请人： Werner Hinn
发明人： Werner Hinn
CPC分类号： H04N11/186 , H03G11/06 , H03K5/08
摘要： SECAM subcarrier demodulator employs a multistage limiter-amplifier to supply two inputs to a signal multiplier, one input being supplied directly and the other input being supplied via a phase shifter which imparts a phase shift of 90.degree. at one of the SECAM subcarrier resting frequencies. Positive feedback is associated with the final amplifier stage of the limiter-amplifier to provide said stage with a hysteresis characteristic ensuring development of a limiter output with a rectangular waveshape having rise and fall times of substantial constancy, independent of input signal amplitude variations. Negative DC feedback from the penultimate amplifier stage to the input amplifier stage of the limiter-amplifier assures desired symmetry of limiting action. Color difference signal output is obtained by low pass filtering of the products of multiplication of the respective signal inputs.
摘要翻译： SECAM副载波解调器采用多级限幅放大器向信号乘法器提供两个输入，一个输入直接提供，另一个输入通过移相器提供，该移相器在SECAM子载波静止频率之一处施加90°的相移。 正反馈与限幅放大器的最终放大器级相关联，以提供具有滞后特性的所述级，确保利用具有相当恒定的上升和下降时间的矩形波形来发展限幅器输出，而与输入信号幅度变化无关。 来自倒数第二放大器级到限幅放大器级的负DC反馈确保了限制动作的期望对称性。 色差信号输出通过对各个信号输入相乘的乘积的低通滤波获得。
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87.发明授权
公开(公告)号：US4101837A
公开(公告)日：1978-07-18
申请号：US795991
申请日：1977-05-11
摘要： A tunable oscillating limiter threshold extension demodulator capable of demodulating video and other wide band width FM signals is described. A steering signal is generated to tune the oscillating limiter in response to the video output signals from an FM discriminator to which input signals from the oscillating limiter are applied. The steering signal is generated so as to be in proper phase relationship to track the frequency of the FM signal for modulating frequencies within certain critical regions and is reduced in amplitude over another region where proper phase relationship is not achievable because of unavoidable delays in the system. The steering signal generating circuit may be provided by a filter having a phase response characteristic such that the total phase lag of the system is small at the low frequency end of the band width and about 360.degree. at the high frequency end of the band width. The filter presents substantial attenuation (in the form of a notch) in the frequency region of the band width where the phase delay may be about 180.degree. and would otherwise provide improper oscillating limiter steering action. In the case of color television signals, for example, significant spectral components of the signal, specifically the components due to the sync and equalizing signals are present in the low frequency end of the signal band width while the significant color or chromatic subcarrier spectral component is at the high frequency end of the signal band width. Accordingly, when applied to tune the band pass filter of the oscillating limiter the frequency to which the oscillating limiter is tuned is caused to substantially match the instantaneous frequency of the color television modulated FM signal at the frequencies of these significant components and the noise threshold in terms of the minimum signal to noise ratio which the demodulator can operate properly is thereby improved.
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88.发明授权Radio receiver having a preselection circuit tuned by a varactor with a variable limiter threshold circuit to attenuate large amplitude signals 失效无线电接收机具有通过可变限幅器阈值电路由变容二极管调谐的预选择电路，以衰减大振幅信号
公开(公告)号：US3968439A
公开(公告)日：1976-07-06
申请号：US571538
申请日：1975-04-25
CPC分类号： H03G11/06 , H03G11/04 , H03G3/3052
摘要： Radio receiver provided with varactor tuning. To maintain the signals across the varactor of the preselection circuit sufficiently small the receiver has a controlled input stage which is connected before the circuit and a limiter which has a controlled threshold voltage and is connected to the input circuit.
摘要翻译： 无线电接收机提供变容二极管调谐。 为了保持预选电路的变容二极管之间的信号足够小，接收器具有被控制的输入级，该控制输入级在电路之前被连接，而限制器具有受控的阈值电压并被连接到输入电路。
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公开(公告)号：US3569740A
公开(公告)日：1971-03-09
申请号：US3569740D
申请日：1966-12-27
申请人： RCA CORP
发明人： AVINS JACK
CPC分类号： H03F3/213 , H03F1/302 , H03F3/347 , H03F3/45071 , H03F3/45479 , H03F2203/45498 , H03F2203/45701 , H03F2203/45722 , H03G11/002 , H03G11/06
摘要： A limiter-amplifier circuit including first and second emitter coupled transistors and an emitter follower (third) transistor having its input direct coupled to the output (collector) of the second transistor. The first transistor is operated as a base input, common collector stage while the second transistor is operated as an emitter input, common base stage. A resistor connected in common to the emitters of the first and second transistors is substantially one-half the value of a resistor connected to the collector of the second transistor. Output load resistance is coupled to the emitter of the emitter follower transistor and an additional resistor is coupled to the collector of the emitter follower to provide substantially symmetrical limiting of input signals supplied to the base of the first transistor.
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公开(公告)号：US3555300A
公开(公告)日：1971-01-12
申请号：US3555300D
申请日：1967-05-22
发明人： OVERLIE PER T
CPC分类号： H03G11/06
摘要： An FM receiver having an amplitude limiter with a pair of diodes for clipping positive and negative going portions of a signal and a semiconductor circuit providing a high-input impedance to the dual diodes and having a constant current output. The semiconductor circuit has a pair of emitter coupled transistors connected to a third transistor connected as a constant current source.
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